applier: send IPROTO_ID to master

We need it to retrieve the default authentication method that should be
used by the applier if not set explicitly in URI. In future, we may also
use it for other things, e.g. fetching the master's name.

The IPROTO_ID request is sent only if the master's version is >= 2.10.0.
An error received in reply to IPROTO_ID is logged, but doesn't abort
replication, because IPROTO_ID is optional.

Needed for #7989

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